This invention relates in general to oral prosthetic implants and in particular to dental prosthetic implants which are surgically implantable and provide support means for crown replacements and artificial teeth.
In order to replace teeth which have been lost, whether by damage from an accident or injury or by disease, dentists and oral surgeons may utilize either a permanent or removable bridge. However, certain situations dictate somewhat more involved corrective measures, such as implanting a partial denture which is one form of prosthetic restoration. A partial denture may be a tooth-borne, tooth and mucosal-borne or mucosal-borne prosthesis, and the design and fit is critical to its suitability for the particular patient because of the relatively high force loads to be exerted upon such prosthetic devices. One of the primary disadvantages of partial dentures is the fact that the partial denture receives marginal load support from the underlying alveolar bone at the vacant tooth site or sites, thus forcing the transfer of abnormal lateral stresses to abutting teeth with destruction of peridontal tissues.
The following listed patents disclose apparata which have been associated with various attempts to implant relatively rigid structures into the mandible. While each may have provided some benefit or improvement to the particular area of technology at the time of their conception, the present invention disclosed herein provides still further benefits and improvements to each of these various prior art devices.
______________________________________ Patent No. Patentee ______________________________________ 3,577,853 Roberts 3,641,671 Roberts 3,777,402 Roberts 3,889,375 Roberts 3,739,476 Roberts 3,950,850 Driskell et al. 2,628,929 German (Bandettini) 3,729,825 Linkow et al. 3,881,251 Valen 4,050,157 Fagan, Jr. et al. 4,121,340 Patrick 3,797,113 Brainin 3,465,441 Linkow 4,024,639 Weiss et al. 3,851,393 Weiss et al. ______________________________________
Roberts (3,577,853) discloses an implant which is designed to be mounted specifically in the ramus or retromolar portion of the mandible or jawbone and includes an elongated main body carrying a post extending up from the forward end of the main body and passing up through the epithelium.
Roberts (3,641,671) discloses a permanent frame for removably supporting an artificial denture for the entire lower jaw. The frame comprises a rigid bar sized and shaped to correspond to the mandible and denture and the bar terminates at each end in a ramus implant and has an integral intraosseous blade at the central portion providing a holding implant in the front of the mandible.
Roberts (3,777,402) discloses a permanent frame for removably supporting an artificial denture in a molar area of the lower jaw when there is a sound natural bicuspid or cuspid tooth adjoining the area. The frame includes a rigid bar with the rear end formed into a ramus implant and the exposed portion of the bar is sized and shaped to conform to the molar area in question.
Roberts (3,889,375) discloses a frame portion for implanting into a correspondingly shaped upwardly extending channel cut longitudinally in the alveolar ridge of the upper jaw. The frame has a rear extension arranged to project through an aperture cut in the pterygoid bone and more particularly in an aperture cut just above the pyramidal process.
Roberts (3,739,476) discloses a denture support frame which includes a rigid bar which is sized and shaped to correspond to the alveolar ridge of the upper jaw. Each end of this main portion is turned approximately 90.degree. to extend a short distance upwardly and is again turned approximately 90.degree. so as to extend forwardly to form an implant which is driven anteriorly into the posterior tuberosity of the maxillary ridge.
Driskell discloses a prosthetic dental implant which is surgically plantable in the maxillary and mandibular alveolar bones. The implant includes a support base with a protruding post onto which one or more prosthetic crown replacements may be mounted. The implant is high-purity, high-density, low-porosity unitary alumina body and includes a serrated-shaped base.
The West German reference discloses a dental implant which is fitted into the jawbone and includes one portion which is inserted into the cancellous tissue beneath the jawbone compact tissue and includes at least one stump portion projecting from this part into the buccal cavity.
Linkow et al. discloses an oral implant of the vented blade type which includes a relatively thin vented blade portion adapted to be driven into a groove in the patient's jawbone and a crown supporting head and a neck portion connecting the crown supporting head to the blade portion.
Valen discloses a prefabricated tooth system which serves as a permenently secured tooth section which is easily removable for purposes of repair or modification. The tooth system comprises a bar which spans the space left by the missing teeth.
Fagen, Jr. et al. discloses a dental implant for anchoring attachments to the jawbone and includes a flat base embedded entirely within the bone tissue of the mandibular or maxillary ridge. A support head is connected to the base by a shank having a necked down portion spaced from the base and confined to the gingival.
Patrick discloses a combination bladevent subperiosteal implant in which the abutment post which bears an artificial tooth or a tooth in a full arch splint is isolated from and only indirectly attached to the bladevent body through a subperiosteal portion of the implant.
Brainin discloses a dental implant member formed of substantially nonporous, isotropic carbon having a textured and dentated lower portion. The implant member is provided with means for attaching an artificial crown section thereto.
Linkow discloses a device for implanting an artificial tooth and includes a blade with an opening therein and a free end defining a sharp edge. A support portion extends up from the blade to which support portion a force may be applied which is distributed over the blade so as to facilitate the implantation of the blade in the jawbone of the patient. Once the blade is implanted, the artificial tooth structure is secured to the support portion which extends up from the gum region.
Weiss et al. (4,024,639) discloses a dental implant which is embedded within a body of acrylic material in a channel formed in the jawbone such that no portion of the implant comes in contact with the bone. The implant includes one or more projecting pins for supporting an artificial tooth and a series of lateral projections which extend into the acrylic material to hold the implant in place.
Weiss et al. (3,851,393) discloses an oral implant of the vented blade type which includes a relatively thin vented blade adapted to be seated into the groove of the patient's jawbone, a crown supporting head and a neck integrally connecting the head to the blade. The blade has a curvature corresponding to the average curvature of a frontal jawbone segment and is inclined relative to the head so that the head remains relatively vertical while the blade follows the jutting angle of the frontal jawbone segment.
One feature required with each of the disclosed apparata is some type of anchoring or securing means for the prosthetic implant. This is typically accomplished by a stake or post having vents or alternatively a serrated or sawtooth contour. Slight variations in the design of such stakes, while appearing to be subtle, can have a significant effect as to the strength and rigidity of the implant. For example, a sawtooth or serrated contoured stake as disclosed by Linkow et al. is desired for ease of insertion but is unfortunately susceptible to migration deeper into the bone with those forces acting on the upper surface of the head. Consequently, it would be an improvement from the standpoint of strength to reverse the direction of the sawtooth so as to act against such forces and prevent deeper migration into the jawbone. The Driskell et al. patent incorporates such a concept but does not also utilize vents which are also beneficial in that they permit the bone to grow into and through the vents thereby locking the implant in place.
The present invention incorporates a variety of improvement features into a single prosthetic implant and the concepts disclosed are suitable as part of a ramus frame as well as an individual tooth replacement. While certain similarities may exist between the invention disclosed herein and various prior art references, the specific combinations described are novel and provide a number of advantages.